A pointing device, such as a mouse, allow a user to point to a position on a screen to interactively position a cursor or select a position on a display surface, such as a display screen or other suitable surface. Such pointing devices are known to be used in desktop computers, mobile devices, laptop computers, cell phones, PDAs, Internet appliances and other devices. The pointer on a display may be textual (e.g., highlighted text) or graphical (e.g., cursor).
User interfaces on portable consumer electronic products are getting more complex. This complexity generally requires more controls for the user to manipulate. However, consumer demands typically require products that are small and compact. It can be difficult to include sufficient controls and still keep the device small enough for consumer acceptance. There is also a practical limit on how small controls, such as buttons, may be placed with respect to each other and still remain operable by an average user's finger.
Two major classes of pointing devices exist on portable consumer electronic products, namely one dimensional and two dimensional pointing devices. A one dimensional pointing device may include, for example, thumbwheels, spinners, sliders, multi-position toggle switches, and rocker switches. These pointing devices are used to select movement in one dimension in a user interface, such as a graphical user interface, or other suitable interface. Movement in one dimension is generally interpreted as one of an up/down, forward/back and next/previous depending on the context of the product.
One dimensional pointing devices, such as wheels, can be constructed to use very little of the inherently limited surface area of a consumer product. For example, the edge of a wheel may be extended through a slot opening in a product housing and permit a user to roll the wheel in both directions by dragging a finger along the wheel edge tangent to its circumference. A disadvantage of such wheel controls is that the slot openings in the housing permit contaminants to enter the product.
Toggle switches and rockers are typically larger than wheels, and they require a surface area pad large enough to receive a user's fingertip. In some cases, rocker switches are implemented as two adjacent buttons linked by a common button bar. These devices can be engineered to preserve the environmental seal of the housing of the product. However, such devices have the disadvantages that they contain moving parts and can take up larger surface areas of the device compared to the other one-dimensional alternatives listed previously.
Two dimensional pointing devices include, for example, track pads, track balls, mice, joy sticks, and other devices. These types of pointing devices are typically used to select movement in two dimensions simultaneously within a user interface. Any two dimensional pointing device can also be used as a one dimensional pointing device if desired by trivially ignoring one of the dimensions sensed by the device. Two dimensional pointing devices are much more versatile than one dimensional pointing devices. Typically, two dimensional pointing devices are used to select and manipulate information in a two dimensional display by indicating a position (X, Y) on the display, where that position (X, Y) is associated with a function by way of a graphical user interface. Alternatively, a two dimensional pointing device can be used to control two independent aspects of a device, such as pitch versus timbre, and ailerons versus rudder, interest rate versus term.
Trackpads are flat surface areas that sense the absolute contact location of the user's fingertip on the flat surface area. A minimum size of a trackpad must therefore be somewhat larger than a user's fingertip to be effective; practically they exceed several times the size of the user's fingertip. An advantage of trackpads is that they usually require very little depth within a device housing with respect to the surface area that they require, and they can be environmentally sealed. However, due to the amount of surface area that trackpads require, they are not typically common on smaller products like handheld devices.
Track balls utilize a rolling sphere to provide a relative motion indication output for a user interface. The user touches the sphere and causes it to roll. The roll angle of the sphere is sensed to determine two-dimensional pointing information. The minimum diameter of a track ball is constrained by, for example, the size of the sensing apparatus used to determine rotation. A disadvantage of track balls is that they require depth within a housing on the same order of the track ball diameter. However, many portable consumer electronic products do not have the necessary depth to accommodate a track ball pointing device and related sensing mechanisms. In addition, track balls cannot be environmentally sealed and thus also permit contaminants to enter the product.
Joy sticks are typically not used in portable consumer electronic products, typically because they must project above the surface of the product and they can generally require significant volume or depth within the product for the sensing mechanisms. A variant of a joy stick, commonly referred to as a joybutton or hat switch, is usually implemented as a two-dimensional rocker switch. Among the disadvantages shared by a joybutton and a hat switch are that the device generally cannot indicate speed or distance, only direction.
The most common type of prior art mouse pointing device (plural: mice) operates substantially like an inverted track ball. Instead of the user touching and rolling the sphere directly, the user moves an entire housing containing the inverted track ball upon an auxiliary flat surface (a mouse pad) separate from the housing. The auxiliary flat surface has a minimum size determined by the size of the mouse housing, and in practice the minimum size of such a mouse pad is significantly larger than a user's palm. In use, the friction between the sphere and the mouse pad causes the sphere to rotate within the housing, at which point the remainder of the operation is similar to a track ball device. In addition to all of the disadvantages of a track ball, such existing prior art mice also appear to have the disadvantage of requiring the auxiliary flat surface, and the sensing of motion is necessarily conducted on the bottom of the housing.
Another prior art mouse implementation requires a fine regularly repeating optical pattern or grid printed on the mouse pad surface, on which the user slides an optical mouse. This type of optical mouse uses sensors necessarily on the bottom surface of the housing that are placed at a specific pitch relative to the grid on the mouse pad surface and thus senses the relative motion of the known grid underneath it and uses that information to sense direction and speed. However, disadvantages of the additional grid surface include the requirement for the mouse pad itself, and that the mouse pad is typically hard to keep clean and free from damage, the mouse pad is typically several times larger than the user's palm, and the user must take care to keep the orientation of the optical mouse consistent with the orientation of the grid on the mouse pad.
Another type of optical mouse such as an IntelliEye Optical Sensor™ marketed by Microsoft Corporation of Redmond, Wash. uses optical sensors and image processing techniques to determine relative motion. As with all other prior art mice implementations, this product requires an auxiliary surface on which to operate. This product is differentiated from the optical grid mouse previously cited in that it does not require a separate optical repeating grid pad and it uses a plurality of sensor arrays and an image processor to determine speed and direction of motion of a flat smooth surface below it. The sensor arrays are thus necessarily positioned on a bottom surface of the optical mouse. A flat sensing window on the bottom of the mouse receives light for the optical sensor arrays. In operation, a flat area, such as the top of a desk, is required to use the mouse. The minimum size of the flat area is at least as large as the mouse housing, which is about the size of a user's palm, and in practice the flat area required is several times larger than a user's palm. As such, an improved display pointing device would be desirable for portable consumer devices.